Example Data Table
| Scenario | Length (ft) | Depth (in) | Method | Soil | Crew | Est. Hours | Rate ($/hr) | Est. Billed Cost |
|---|---|---|---|---|---|---|---|---|
| Backyard french drain | 60 | 18 | Mini-excavator | Medium | 2 | 10.2 | 35 | $410 |
| Side yard tight access | 45 | 24 | Hand digging | Hard | 2 | 22.6 | 40 | $1,040 |
| Channel drain near driveway | 35 | 10 | Mini-excavator | Easy | 3 | 6.1 | 38 | $265 |
These examples are illustrative estimates only. Real conditions, disposal distance, and utility conflicts can materially change labor hours.
Formula Used
Linear work hours
LinearHours = Length(ft) × BaseHoursPerFt × DepthMult × WidthMult × SoilMult × AccessMult × SlopeMult
Total labor hours
TotalHours = SetupHours + LinearHours + FabricHours + GravelHours + PipeHours + RestoreHours + BasinHours + CleanoutHours + OutletHours
Costs
LaborCost = TotalHours × LaborRate × (1 + Overtime%/100)
BilledCost = LaborCost × (1 + Markup%/100)
How to Use This Calculator
- Enter the drain length and choose feet or meters.
- Set trench width and depth based on your details.
- Select drain type and excavation method for production rates.
- Choose soil, access, and slope to apply multipliers.
- Add counts for basins, cleanouts, and outlets.
- Toggle optional scope items that match your work.
- Enter labor rate, overtime premium, and markup.
- Press Calculate to view hours, cost, and breakdown.
Accurate estimates help you plan drainage work confidently today.
Drainage Labor Planning Guide
1) Why labor hours drive drainage budgets
For small residential drainage, labor is often the largest controllable cost. A 50–80 ft run can take one crew-day when access is open and soil is workable. When conditions tighten, labor hours can double even if material quantities stay similar, so hour forecasting protects margin.
2) Typical productivity ranges by method
Hand excavation is slower because spoil handling and trench shaping are continuous. Many crews plan roughly 0.20–0.35 labor-hours per foot for hand work depending on depth and soil. With compact equipment, production often improves to about 0.07–0.14 labor-hours per foot for comparable trenching.
3) Trench depth and width effects
Depth increases the time to excavate, manage trench walls, and backfill safely. This calculator treats 18 inches as a baseline and increases effort when depth rises. Width also matters: wider trenches mean more spoils, more gravel handling, and more shaping time, especially in confined yards.
4) Soil difficulty as a multiplier
Soil changes daily output. Easy sandy soils can improve pace, while clay and rocky material slows trenching and may require extra shaping. Many estimators apply a 10–25% swing for soil conditions. Recording local job history helps you calibrate the multiplier that matches your crew.
5) Access and hauling realities
Open access supports equipment use, short wheelbarrow runs, and cleaner staging. Tight access adds handling steps and can force hand digging. A practical way to estimate is to add 10–20% when access is limited, then verify by measuring disposal distance and staging limitations before finalizing.
6) Add-ons that quietly add hours
Fabric placement, gravel leveling, pipe assembly, and outlets are small tasks individually, but together they add meaningful hours. For example, gravel placement can add about 0.02–0.03 hours per foot depending on lift thickness and compaction. Basins and cleanouts add fixed time per unit.
7) Crew sizing and schedule conversion
Total labor-hours become schedule time by dividing by crew capacity. A two-person crew working eight hours produces 16 labor-hours per day. If your estimate is 24 labor-hours, plan about 1.5 crew-days. This step is essential for coordinating equipment rentals and client expectations.
8) Pricing with rate, overtime, and markup
Use a fully burdened labor rate that includes wages, payroll taxes, and supervision. Apply overtime premium only when your schedule demands it. Markup is then applied to labor cost to reach a billed price. Keep your assumptions visible so you can compare bids and refine estimates over time.
FAQs
1) What labor rate should I enter?
Use a fully burdened hourly rate, not just wages. Include payroll taxes, insurance, supervision, and routine overhead. If you track real job costs, base the rate on your average labor burden over the last few projects.
2) How do I choose hand digging versus equipment?
Select hand digging when access is tight, utilities are dense, or equipment cannot reach the trench line. Choose compact equipment when you can stage safely and spoils removal is straightforward. Equipment usually reduces hours significantly.
3) Why does trench depth increase hours so much?
Deeper trenches require more excavation volume, more wall shaping, slower spoil handling, and safer backfill. Depth also increases the chance of utility conflicts and water seepage. Those factors reduce daily production even for experienced crews.
4) Should I include fabric, gravel, and pipe toggles?
Yes, when those tasks are in your scope. Even short runs require time for fabric placement, gravel leveling, and pipe assembly. Leaving them off can understate labor. Toggle surface restoration if you include sod or mulch touchups.
5) How do basins and cleanouts affect the estimate?
They add fixed time for excavation, setting, connecting fittings, and compacting. They also slow the trenching pace near tie-ins. If your sites require multiple basins, the fixed hours can become a large share of the total.
6) What does “crew-days” mean here?
Crew-days convert labor-hours into calendar time using your crew size and hours per day. For example, 20 labor-hours with two people at eight hours/day equals 1.25 crew-days. It helps plan rentals and delivery timing.
7) Can I calibrate the factors to my crew?
Absolutely. Track actual hours per foot for common conditions and adjust the base hours and multipliers to match your results. The best estimates come from local history combined with consistent scope definitions across jobs.